Agriculture officials in Northeastern states are gearing up for another bout with late blight, a deadly fungal disease.

Late blight hit most New England states this summer and infected tomato and potato plants as far south as Alabama.

“I suspect the spread of the disease this year was largely the result of the unusually cold, wet summer weather,” said Tim Schmalz, state plant pathologist for the Vermont Agency on Agriculture, Food and Markets, Montpelier. “Late blight shows up to some degree every year but usually late in the season.”

Vermont’s commercial grower-shippers were not seriously affected by late blight. Growers of field crops applied a fungicide to tomato and potato plants, Schmalz said, and the hothouse growers have the luxury of a closed system.

“The disease caught a lot of people off guard, because we haven’t seen it in the northeast for a great number of years, at least not to the extent we did this year,” he said. 

Even if the Northeast enjoys a more normal summer in 2010, late blight will be a problem next summer due in large part to the recession, he said.

“Many people planted their own potato and tomato gardens this summer to save a few bucks,” Schmalz said. “Unfortunately, many of them haven’t had experience with disease management, and by the time their plants were infected, it was too late to save them.”

The conditions were ideal for spreading the disease.

“It was just the perfect storm of weather conditions and an abundance of unprotected potato and tomato plants in backyard gardens,” Schmalz said.

Late blight, the disease that was responsible for the Irish Potato famine in the 19th century, is caused by spores that under certain weather conditions can travel on the wind as much as 10 miles a day, Schmalz said.

It also spreads in the potato industry when spores attach themselves to a tuber as the fungus is washed into the soil or when the potato comes into contact with infected leaves during harvest and that tuber is used for planting the next year’s crop.

“When the tuber begins to grow, that triggers the pathogen to become active and it infects the new plant — then spreads to others,” Schmalz said

Helping to spread the disease this summer was a distributor who shipped infected tomato plants to retailers throughout the northeast, he said.

The Vermont Agency of Agriculture, Food and Markets plans to use the news media in the spring to urge home gardeners to treat their plants, Schmalz said.   

“It’s easy to control the disease by spraying with fungicides,” he said.